The present invention relates to lasers and, more particularly, to an improved phase coupled waveguide laser.
Since the advent of the Space Defense Initiative (SDI) there has been an increasing need for a practical high power, long range CO2 laser radar source. Prior art attempts to meet the need for such a laser radar source have used a linear phase coupled waveguide configuration. Linear phase coupled waveguide lasers have been demonstrated by many researchers to provide stable output with as many as three laser waveguide bores coherently coupled. When a photon leakage path is introduced between adjacent, closely spaced waveguide bores, the laser output behaves as if a single device were operating. This attribute makes the coupled waveguide laser a possible candidate for a high power laser radar source in a compact package.
Research work at United Technology Research Center (UTRC) resulted in a five-bore waveguide laser. It employed three central bores and two outside bores in a linearly configured waveguide laser. Unfortunately, researchers were unable to phase lock this five-bore waveguide laser. The researchers at UTRC attributed this failure to the different gain distribution for the two outside bores adjacent to the cooling wall as compared to the three central bores. The conclusion reached is that it is difficult to scale up linear phase coupled waveguide configurations to high power and at the same time maintain a compact size. This was demonstrated when researchers scaled a linear phase coupled waveguide up to five waveguide bores and failed to phase lock them together.
Accordingly, it is an objective of the present invention to provide an improved phase coupled waveguide CO2 laser suitable for use as a compact, high power, long range laser radar source. Another objective of the invention is the provision of a phase coupled waveguide laser having a symmetrical arrangement. A further objective of the present invention is to provide a phase coupled waveguide laser that ensures the same physical condition for all bores. Yet another objective of the invention is the provision of a phase coupled waveguide laser having a design that is easily scalable. A still further objective of the present invention is to provide an improved phase coupled waveguide CO2 laser that is compact.